What is number in brackets for example number 3 in sda5[3]? It is possible to change this number? I think that I had next state:
md0 : active raid1 sda1[0] sdb1[1]
7806912 blocks super 1.2 [2/2] [UU]
md1 : active raid1 sda5[0] sdb5[1]
480441152 blocks super 1.2 [2/2] [UU]
before my experiments.